Field of the Invention
The present invention relates to a toner used in electrophotographic methods, static recording methods, and toner jet recording methods.
Description of the Related Art
Reducing energy consumption has in recent years also been regarded as a major technical problem for electrophotographic devices, and significant reductions in the amount of heat required by the fixing apparatus have thus been investigated. Accordingly, there is increasing need for the toner to be capable of undergoing fixing at lower energies, i.e., for “low-temperature fixability”. In addition, the medium that has been subjected to fixing is frequently also placed in a severe environment, e.g., high temperatures and/or high humidities, and as a result it is also crucial with regard to the toner that medium-to-medium adhesion not occur even when storage in a severe environment is carried out (heat-resistant storability).
In order to improve the low-temperature fixability and heat-resistant storability of toners, the method of incorporating a crystalline resin in the binder resin has been investigated in recent years. The amorphous resins generally used as binder resins for toners do not exhibit a clear endothermic peak in measurement with a differential scanning calorimeter (DSC), but when they contain a crystalline resin component an endothermic peak caused by the melting point is seen in the DSC measurement. Due to the regular arrangement of their molecular chains, crystalline resins undergo almost no softening at temperatures below the melting point, while at higher temperatures bounded by the melting point the crystals abruptly melt and an abrupt decline in the viscosity occurs in association with this. As a consequence, they are receiving attention as materials that have an excellent sharp melt property and that combine heat-resistant storability with low-temperature fixability.
However, crystalline resins are high molecular weight materials, and, due to the occurrence of scatter in their molecular weight, molecular chains are produced that do not undergo regular arrangement. Thus, it is known that a tail ends up being produced on the low-temperature side of the endothermic peak due primarily to a low molecular weight component. This causes a lowering of the heat-resistant storability of the toner, and as a consequence measures have been taken to raise the crystallinity in the toner.
Japanese Patent Application Laid-open No. 2012-042939 provides a toner in which the crystallinity of the crystalline resin in the toner particle has been raised by the execution, after toner particle production, of a heat treatment at a specific temperature lower than the melting point of the crystalline resin, i.e., an annealing treatment. The heat-resistant storability is improved by doing this.